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https://issues.apache.org/jira/browse/MAHOUT-687?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13030595#comment-13030595
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Lance Norskog commented on MAHOUT-687:
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By popular demand, a less ambitious version. Four topics:
* SamplingLongPrimitiveIterator used one common Random which cause the unit
test "deterministic seed" trick fail for some unknown reason. Changed class to
use one Random per instance.
* RandomUtils had a private WeakHashMap out of different RandomWrappers that it
built. It never used the map.
RandomWrapper does exactly what it used to do, with one change and one addition:
* setSeed(long x) now throws UnsupportedOperationException, because all of the
Uncommons RNG classes ignore setSeed(long x). Yes. All of them.
* You can now pull the seed that RandomWrapper makes so that you can make
another Uncommons RNG object, or use it for any purpose.
> Random generator objects- slight refactor
> -----------------------------------------
>
> Key: MAHOUT-687
> URL: https://issues.apache.org/jira/browse/MAHOUT-687
> Project: Mahout
> Issue Type: Improvement
> Reporter: Lance Norskog
> Priority: Minor
> Attachments: MAHOUT-687.patch, MAHOUT-687.patch
>
>
> Problems:
> * Uncommons MersenneTwisterRNG, the default RandomUtils.getRandom(), ignores
> setSeed without throwing an error.
> * The project wants to move off Uncommons anyway.
> This patch uses the org.apache.commons.math.random.RandomGenerator classes
> instead of org.apache.uncommons.maths.RepeatableRNG classes.
> Testcases: All math test cases pass except for
> org.apache.mahout.math.stats.LogLikelihoodTest.
> Other package tests fail that are mostly about testing random-oriented
> classes; not a surprise.
> Almost all tests that use random numbers in algorithms still pass; this is a
> good sign of their stability.
> .
> Still, a lot of tests have to be fiddled to make this commit.
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